Author Topic: Voltmeter reading overcharged  (Read 612 times)

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Offline ttbennett14

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Voltmeter reading overcharged
« on: June 22, 2021, 08:15:01 PM »
Hey guys,

New to the forum but a long time lurker. I’ve tried looking all over the place for this answer but haven't seem to find the answer to my problem.

About two weeks ago i forgot to hit the kill switch on my 550 and it drained the LiPO battery. When i went to go for a ride that day (before I realized what happened) I noticed the voltmeter gauge on my bike was reading 16v. Chalked it up to it being the battery that needed replacing.

Fast forward a week. Got my new battery, hooked it up, still read 16v. Pulled and tested the battery, it checked out. I went for a short ride, maybe 5 minutes, and now the gauge is reading 20v+? Tested all fuses, regulator, and stator...all within spec. Could it possibly be the gauge itself? For continuity purposes, I have the moto MUnit.

If I’m being an idiot and missing something obvious, feel free to make sure I know.

Offline bryanj

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Re: Voltmeter reading overcharged
« Reply #1 on: June 22, 2021, 10:40:31 PM »
First connect the voltmeter direct to the battery with nothing else connected, if it reads 12v ish i would guess your reg is shot
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline ttbennett14

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Re: Voltmeter reading overcharged
« Reply #2 on: June 23, 2021, 06:45:40 AM »
Did that as well, it read 13v. Going to put it on a tester just to cover my bases and make sure I didn’t miss anything THAT simple. I have a suspicion it’s the reg as well even though it tested out fine.

Offline TwoTired

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Re: Voltmeter reading overcharged
« Reply #3 on: June 23, 2021, 07:15:38 AM »
For the regulator to work it must know voltage at the battery.  Check for what the regulator “sees” to what the battery terminals actually have.  There can be circuit pathway issues in both the supply path (switched 12V) and return path (ground) that lose voltage potential.  If the regulator is detecting true batt voltage too high, yet still driving the voltage higher, it has failed.  This can be determined by checking the vreg drive to the alternator field.  As batt voltage gets too high, alternator drive voltage must be reduced at the alternator.  As you do not have stock wiring, check for wire route errors.

Cheers!
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline samm_j2

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Re: Voltmeter reading overcharged
« Reply #4 on: June 23, 2021, 08:31:17 PM »
Are you running a lithium battery? Did you update the reg/rec for the lithium battery?? I believe the stock reg and rec will over charge the lithium battery. Make sure you have your horn hooked up if you are running an M-unit, if the M-unit sees too much voltage it will blare the horn. This is a warning to kill the bike immediately. Ask me how I know. I melted an antigravity and fried an Munit due to a faulty reg/rec....